WASHINGTON — A Soyuz spacecraft is en route to the International Space Station, two days after a rare last-minute launch scrub.

A Soyuz-2.1a rocket lifted off from the Baikonur Cosmodrome at 8:36 a.m. Eastern March 23. It placed the Soyuz MS-25 spacecraft into orbit about nine minutes later.

Soyuz MS-25 is commanded by Roscosmos cosmonaut Oleg Novitskiy with NASA astronaut Tracy C. Dyson and Marina Vasilevskaya, a Belarusian spaceflight participant, also on board. The spacecraft is scheduled to dock with the station’s Prichal module at 11:09 a.m. Eastern March 25.

The launch was scheduled for March 21, but the countdown was halted just 20 seconds before liftoff. Roscosmos said several hours later that the launch was called off because of a low voltage reading in the launch vehicle. There had been no record of a scrub so late in the countdown of a crewed Soyuz launch before this incident.

At a March 22 briefing about the upcoming CST-100 Starliner crewed test flight to the station, Dana Weigel, NASA ISS deputy program manager, said at that time that Roscosmos was still troubleshooting the issue, but Roscosmos announced later in the day the launch had been rescheduled for the next day.

NASA spokesman Rob Navias said in NASA TV coverage of the second launch attempt that batteries were replaced and tested in the Soyuz rocket’s first stage after the scrub, allowing the launch to proceed.

The two-delay launch delay will mean a four-day delay in the arrival of the crew to the station. The original launch was planned to allow the Soyuz to fly a fast approach to the station, arriving about three hours after launch. That trajectory is not available on this launch attempt, meaning the crew will take a more conventional two-day approach to the station.

Once docked to the station, Novitskiy and Vasilevskaya will remain for 12 days, returning in the Soyuz MS-24 spacecraft currently there with NASA astronaut Loral O’Hara, who launched to the station in that spacecraft in September along with Russian cosmonauts Oleg Kononenko and Nikolai Chub. That departure is scheduled for April 6. Kononenko and Chub will remain on the station an additional six months, returning in Soyuz MS-25 with Dyson.

The Soyuz MS-25 launch took place a little more than an hour after a Dragon cargo spacecraft, flying the CRS-30 commercial cargo mission, docked with the station. That docking, with the zenith port of the Harmony module, took place at 7:19 a.m. Eastern, about 10 minutes ahead of schedule. The spacecraft launched March 21 on a Falcon 9 and is delivering more than 2,800 kilograms of supplies, experiments and hardware to the station.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...